Negative electrode material and preparation method thereof, negative electrode plate, sodium ion battery and electronic equipment

Abstract

The embodiment of the invention provides a negative electrode material and a preparation method thereof, a negative electrode plate, a sodium ion battery and electronic equipment, and relates to the technical field of batteries. The electrode material comprises carbonaceous particles, the carbonaceous particles comprise first amorphous carbon particles and second amorphous carbon particles, the first amorphous carbon particles are of a blocky structure, the second amorphous carbon particles are of a sphere-like hard carbon structure, the Dv50 particle size of the second amorphous carbon particles is smaller than that of the first amorphous carbon particles, and the Dv50 particle size of the second amorphous carbon particles is smaller than that of the first amorphous carbon particles. And the sphericity of the second amorphous carbon particles B is 0.7-1.0. According to the negative electrode material, the compaction density can be improved on the basis of ensuring high sodium storage capacity.

Description

Technical Field

[0001] This application relates to the technical field of batteries. More specifically, this application relates to a negative electrode material and its preparation method, a negative electrode sheet, a sodium-ion battery, and an electronic device. Background Art

[0002] The development of large-scale energy storage technology will be a trillion-dollar market in the future. Currently, electrochemical energy storage technology has good application prospects in large-scale energy storage demonstration projects, 5G base stations, etc. However, the cost of energy storage systems mainly based on lithium-ion batteries is relatively high, and the current lithium battery industry faces serious resource limitations. Sodium-ion batteries have rich raw material reserves, low costs, and high safety, and are expected to replace lithium-ion batteries in large-scale energy storage.

[0003] As an important part of sodium-ion batteries, the performance of the negative electrode material largely determines the energy density and cycle life of the battery. Currently, the capacity of the positive electrode material of sodium-ion batteries is relatively low. Therefore, the capacity utilization of the negative electrode is crucial for improving the energy density of the entire battery cell.

[0004] Limited by the layer spacing, graphite-based materials are not suitable as the negative electrode material for sodium-ion batteries. Hard carbon materials show a higher degree of disorder during high-temperature treatment, have a rich sodium storage environment, high reversible capacity, small volume change during sodium deintercalation / insertion, and low redox potential, etc., and are expected to become the first commercially available negative electrode material for sodium-ion batteries. However, hard carbon materials have the defect of low tap density. Therefore, for hard carbon materials, how to improve the tap density while taking into account the high sodium storage capacity is an urgent problem to be solved in this field. Summary of the Invention

[0005] The embodiments of this application provide a negative electrode material and its preparation method, a negative electrode sheet, a sodium-ion battery, and an electronic device. Due to its unique composite structure, this negative electrode material can improve the tap density while ensuring a high sodium storage capacity.

[0006] To achieve the above object, the embodiments of this application adopt the following technical solutions:

[0007] In a first aspect, the embodiments of this application provide a negative electrode material, which includes carbonaceous particles. The carbonaceous particles include first amorphous carbon particles and second amorphous carbon particles. The first amorphous carbon particles are in a block structure, and the second amorphous carbon particles are in a spherical hard carbon structure. The Dv50 particle size of the second amorphous carbon particles is smaller than that of the first amorphous carbon particles, and the sphericity of the second amorphous carbon particles B is 0.7 - 1.0.

[0008] Since the carbonaceous particles contain first amorphous carbon particles and second amorphous carbon particles, the structure of the second amorphous carbon particles is spherical, and the Dv50 particle size of the second amorphous carbon particles is smaller than that of the first amorphous carbon particles. Therefore, the second amorphous carbon particles can fill the gaps between multiple first amorphous carbon particles, thereby increasing the tap density. And since amorphous carbon particles are used, this application can achieve an increase in tap density while ensuring a high sodium storage capacity.

[0009] In a possible design, the ratio of the Dv50 particle size of the first amorphous carbon particles to that of the second amorphous carbon particles is 1:(0.1 - 0.6).

[0010] In a possible design, the mass mixing ratio of the first amorphous carbon particles to the second amorphous carbon particles is 10:(0.5 - 7).

[0011] In a possible design, the Dv50 of the first amorphous carbon particles is 4.0 μm - 10.0 μm, and the particle size distribution value S1 of the first amorphous carbon particles is 1.0 - 1.8, where the particle size distribution value S1 = (Dv90 - Dv10) / Dv50.

[0012] In a possible design, the Dv50 of the second amorphous carbon particles is 1.0 μm - 4.0 μm, and the particle size distribution value S2 of the second amorphous carbon particles is 0.5 - 1.6, where the particle size distribution value S2 = (Dv90 - Dv10) / Dv50.

[0013] In a possible design, the particle size distribution detection PSD (particle size distribution) detection result of the negative electrode material has a bimodal characteristic.

[0014] In a second aspect, an embodiment of this application provides a method for preparing a negative electrode material, which mainly includes:

[0015] Subject the hard carbon precursor to pretreatment, pre-carbonization, pulverization, first high-temperature carbonization, and screening and demagnetization to obtain first amorphous carbon particles with a block structure;

[0016] Use the polysaccharide hydrothermal method and in-situ polymerization of polymer resin to prepare a spherical amorphous carbon precursor, and subject the spherical amorphous carbon precursor to second high-temperature carbonization, pulverization, and screening and demagnetization to obtain second amorphous carbon particles with a spherical hard carbon structure;

[0017] Mix the first amorphous carbon particles and the second amorphous carbon particles to obtain the negative electrode material.

[0018] A possible design for obtaining a negative electrode material by mixing a first amorphous carbon particle and a second amorphous carbon particle includes: mixing the first amorphous carbon particle and the second amorphous carbon particle according to a mass ratio of 10:(0.5 - 7) to obtain the negative electrode material.

[0019] A possible design is that the Dv50 particle size of the second amorphous carbon particle is smaller than that of the first amorphous carbon particle.

[0020] A possible design is that the ratio of the Dv50 particle sizes of the first amorphous carbon particle and the second amorphous carbon particle is 1:(0.1 - 0.6).

[0021] A possible design is that the sphericity of the second amorphous carbon particle is 0.7 - 1.0.

[0022] A possible design is that the pre - carbonization temperature is set to 300°C - 600°C, and the temperature of the first high - temperature carbonization is set to 1200°C - 1500°C.

[0023] A possible design is that the temperature of the second high - temperature carbonization is set to 1200°C - 1500°C.

[0024] The negative electrode material obtained by the above - mentioned preparation method can achieve an increase in the compaction density while ensuring a high sodium storage capacity.

[0025] In a third aspect, an embodiment of the present application provides a negative electrode sheet, which includes a negative electrode current collector and a negative electrode material layer provided on at least one side of the negative electrode current collector. The negative electrode material layer includes the negative electrode material mentioned in the first aspect or the negative electrode material prepared by the preparation method in the second aspect.

[0026] In a fourth aspect, an embodiment of the present application provides a sodium - ion battery, which includes a positive electrode sheet, a negative electrode sheet, a separator located between the positive electrode sheet and the negative electrode sheet, and an electrolyte. The electrolyte is filled between the positive electrode sheet and the negative electrode sheet. The negative electrode sheet includes the negative electrode material mentioned in the first aspect or the negative electrode material prepared by the preparation method mentioned in the second aspect.

[0027] In a fifth aspect, an embodiment of the present application further provides an electronic device, which includes a housing, and electronic components and a battery accommodated in the housing. The battery powers the electronic components, and the battery includes the sodium - ion battery mentioned in the fourth aspect.

[0028] These and other aspects of the present application will be more concise and understandable in the description of the specific embodiments. Description of the Drawings

[0029] To more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the accompanying drawings required in the description of the embodiments or the prior art. Obviously, only a part of the embodiments of the present application are reflected in the following drawings. For those of ordinary skill in the art, without creative efforts, other embodiments of the present application can be obtained based on these drawings. And all these embodiments or implementation manners are within the protection scope of the present application.

[0030] Figure 1 Schematic structural diagram of the sodium-ion battery provided by the embodiment of the present application;

[0031] Figure 2 Schematic structural diagram of a negative electrode material provided by the embodiment of the present application;

[0032] Figure 3 Flow chart for preparing the high-compaction sodium-ion amorphous carbon negative electrode material provided by the embodiment of the present application;

[0033] Figure 4 Microstructure diagram of the high-compaction sodium-ion amorphous carbon negative electrode material provided by the embodiment of the present application;

[0034] Figure 5 Microstructure section diagram of the high-compaction sodium-ion amorphous carbon negative electrode material provided by the embodiment of the present application. Specific embodiments

[0035] The following will clearly and completely describe the technical solutions in the embodiments of the present application in conjunction with the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the protection scope of the present application.

[0036] The solution described in the embodiment of the present application is to more clearly illustrate the technical solution of the present application and does not constitute a limitation to the technical solution of the present application. Those of ordinary skill in the art know that the technical solution provided by the embodiment of the present application is also applicable to similar technical problems.

[0037] Those skilled in the art can understand that terms such as "first", "second", "S01", "S02", etc. do not limit the quantity and execution order, and the terms "first", "second", etc. do not necessarily limit being different. At the same time, in some embodiments of the present application, words such as "exemplary" or "for example" are used to represent examples, illustrations or explanations. Any embodiment or design solution described as "exemplary" or "for example" in the embodiments of the present application should not be construed as being more preferred or having more advantages than other embodiments or design solutions. Rather, the use of words such as "exemplary" or "for example" is intended to present relevant concepts in a specific manner for easy understanding.

[0038] For ease of understanding, some descriptions of concepts related to the embodiments of the present application are given as examples for reference. As shown below:

[0039] Cathode: In a primary battery, the electrode with a higher electrode potential where the current flows out is the cathode, which gains electrons and undergoes reduction. In an electrolytic cell, the cathode is the electrode connected to the positive pole of the power supply, which loses electrons and undergoes oxidation.

[0040] Anode: In a primary battery, the electrode with a lower electrode potential where the current flows in is the anode, which loses electrons and undergoes oxidation. In an electrolytic cell, the anode is the electrode connected to the negative pole of the power supply, which gains electrons and undergoes reduction.

[0041] Electrolyte: Provides a medium for ion exchange between the positive and negative electrodes of the battery.

[0042] Separator: The main function of the separator is to separate the positive and negative electrodes of the battery to prevent short - circuit due to contact between the two poles. In addition, it also has the function of allowing electrolyte ions to pass through. Energy density: Used to indicate the amount of energy stored in a unit volume of a substance or in a unit mass of a substance. The energy density of a battery is the electrical energy released per unit volume or mass on average by the battery. The energy density of a battery is generally divided into two dimensions: weight energy density and volume energy density. The greater the energy density of the battery, the more electrical charge is stored per unit volume or weight.

[0043] Compacted density: Refers to the compacted density of the electrode after the material is made into an electrode sheet. Generally speaking, within the allowable compaction range of the material, the greater the compacted density of the electrode sheet, the higher the capacity of the battery. Therefore, the compacted density is also regarded as one of the reference indicators for the energy density of the material.

[0044] Tap Density: It is the density of a material after vibration. Specifically, tap density is one of the important indicators of powder quality. Tap density measurement refers to filling a certain amount of powder into a container and vibrating it regularly under certain conditions to compress the voids between particles as much as possible until the voids between particles can no longer be reduced. When the volume of the powder in the container no longer decreases, the volume of the powder is read out, and then the weight of the powder is divided by this volume to obtain the tap density of the powder.

[0045] Specific Capacity: It mainly includes mass specific capacity and volume specific capacity. Among them, mass specific capacity is the ratio of capacity to mass, and mass specific capacity is used to indicate the amount of electricity that a battery or active material per unit mass can release. Volume specific capacity is the ratio of capacity to volume, and volume specific capacity is used to indicate the amount of electricity that a battery or active material per unit volume can release.

[0046] La value: It is the average size of a graphite crystal along the a-axis direction;

[0047] Lc value: It is the thickness of the graphite plane stacked along the c-axis direction perpendicular to it. Depending on the type of carbon, it ranges from as small as 1 nanometer to as large as 10 micrometers or more, and is generally determined by X-ray diffraction.

[0048] D002 interlayer spacing: It refers to the distance between the layered structures in a material.

[0049] Coulombic efficiency: Also known as discharge efficiency, Faraday efficiency or current efficiency, it is the ratio of the discharge capacity of a battery to the charge capacity during the same cycle, that is, the percentage of the discharge capacity to the charge capacity. The initial coulombic efficiency (ICE) is a performance indicator used to quantify the negative electrode material of a battery, that is, the ratio of the discharge capacity to the charge capacity during the first charge-discharge cycle of the battery. As the charge-discharge cycle progresses, the battery's charge always decays, so the initial coulombic efficiency corresponds to the peak of the battery's life.

[0050] Sphericity: A parameter used to characterize the particle morphology. The closer a particle is to a sphere in morphology, the closer its sphericity is to 1. Its specific value refers to the ratio of the surface area of a sphere with the same volume as the object to the surface area of the object.

[0051] Membrane resistance: It is used to indicate a resistance device applied to a battery or other electronic devices, and its resistance value is determined by factors such as membrane material, membrane thickness, membrane area, temperature, humidity, etc. In a battery, the membrane resistance mainly plays a role in regulating current and protecting the battery.

[0052] Dv50: It is used to indicate the particle size corresponding to when the cumulative particle size distribution percentage of a sample reaches 50%.

[0053] Dv10: It is used to indicate the particle size corresponding to when the cumulative particle size distribution percentage of the sample reaches 10%.

[0054] Dv90: It is used to indicate the particle size corresponding to when the cumulative particle size distribution percentage of the sample reaches 90%.

[0055] Amorphous carbon: Also known as transitional carbon, it refers to carbon materials with very low graphitization degree and crystallization degree, approximately in an amorphous form (or without a fixed shape and periodic structural rules). Amorphous carbon has characteristics such as large interlayer spacing and disordered microcrystalline structure, and is widely used in fields such as activated carbon, fuels, metallurgy, and sodium-ion batteries. According to the different degrees of difficulty in graphitization, amorphous carbon can be divided into two categories: soft carbon and hard carbon. Among them, soft carbon, also known as easily graphitizable carbon, refers to carbon that can be graphitized after high-temperature treatment, and hard carbon, also known as non-graphitizable carbon, refers to carbon that cannot be graphitized after high-temperature treatment above 2800 degrees Celsius. The internal crystal arrangement of hard carbon is disorderly and has more pores. Due to its structural characteristics, the sodium storage capacity of hard carbon is better than that of soft carbon, so it has become an ideal negative electrode material for sodium-ion batteries.

[0056] The embodiments of the present application provide a sodium-ion battery. Figure 1 It is a schematic structural diagram of the sodium-ion battery provided by the embodiments of the present application. As Figure 1 shown, the sodium-ion battery includes a positive electrode sheet 10, a negative electrode sheet 20, a separator 30, and an electrolyte 40. Among them, the separator 30 is disposed between the positive electrode sheet 10 and the negative electrode sheet 20, and the electrolyte 40 is filled between the positive electrode sheet 10 and the negative electrode sheet 20 and wets the separator 30. During charging, sodium ions are removed from the positive electrode material 102 of the positive electrode sheet 10, and after passing through the electrolyte 40, they are embedded into the negative electrode material 202 of the negative electrode sheet 20; during discharging, sodium ions are removed from the negative electrode material 202, and after passing through the electrolyte 40, they are inserted into the positive electrode material 102. Among them, the positive electrode material 102 and the negative electrode material 202 are the main parts for the sodium-ion battery to play the energy storage function, and the negative electrode material 202 is also the most direct embodiment of the energy density, cycle performance, and safety performance of the battery cell.

[0057] Continue to refer to Figure 1 , in the sodium-ion battery provided by the embodiments of the present application, the separator 30 blocks the passage of electrons and allows ions to pass through. The separator 30 includes, but is not limited to, single-layer polypropylene (PP), single-layer polyethylene (PE), double-layer PP / PE, double-layer PP / PP, triple-layer PP / PE / PP, and ceramic-coated PE, etc. In the sodium-ion battery, the electrolyte 40 is the transmission medium for sodium ions to transmit between the positive electrode sheet 10 and the negative electrode sheet 20.

[0058] As Figure 1As shown, the positive electrode sheet 10 includes a positive electrode current collector 101 and a positive electrode material layer coated on the surface of the positive electrode current collector 101. In addition to the positive electrode material 102, the positive electrode material layer may also include a certain amount of binder, conductive agent and other components.

[0059] Among them, the positive electrode current collector 101 can be a metal foil, such as aluminum foil, gold foil, platinum foil, etc. The positive electrode material 102 can reversibly intercalate or deintercalate sodium ions. The positive electrode material 102 includes but is not limited to at least one of layered sodium transition metal oxides, Prussian white compounds, Prussian blue compounds, and sodium polyanion compounds.

[0060] Sodium transition metal oxides such as sodium nickel iron manganese (NaNi1 / 3Fe1 / 3Mn1 / 3O2, NFM111), Prussian white compounds such as (Na2Mn[Fe(CN)6], PBA), Prussian blue compounds such as (NaMn[Fe(CN)6], PBA), and sodium polyanion compounds such as sodium iron phosphate (NaFePO4, NFP), sodium iron sulfate (Na2Fe2(SO4)3, NFS). The binder can be, for example, polyvinylidene fluoride (poly 1,1-difluoroethylene, PVDF), and the conductive agent can be, for example, conductive carbon black (super P), graphite, amorphous carbon, carbon nanotubes, carbon fibers, graphene, etc. The positive electrode current collector 101, positive electrode material 102, binder, and conductive agent used to prepare the positive electrode sheet 10 are only exemplary descriptions, and the embodiments of the present application are not limited thereto. Taking the positive electrode material 102 as an example, theoretically, it can be a compound that can reversibly intercalate / deintercalate sodium ions.

[0061] Continue to refer to Figure 1 , in the sodium ion battery provided by the embodiment of the present application, the negative electrode sheet 20 includes a negative electrode current collector 201 and a negative electrode material layer coated on the surface of the negative electrode current collector. In addition to the negative electrode material 202, the negative electrode material layer may also include a certain amount of binder, conductive agent and other components. Among them, the negative electrode current collector 201 can be a metal foil, such as copper foil, aluminum foil, gold foil, platinum foil, etc. The conductive agent can be, for example, acetylene black, graphite, amorphous carbon, etc. It should be noted that the negative electrode current collector 201, binder, and conductive agent used to prepare the negative electrode sheet 20 are only exemplary descriptions, and the embodiments of the present application are not limited thereto.

[0062] In an embodiment of the present application, refer to Figure 2 , the negative electrode material 202 may include carbonaceous particles, and the carbonaceous particles may include first amorphous carbon and second amorphous carbon. Among them, the first amorphous carbon has a block structure, and the second amorphous carbon has a spherical hard carbon structure. The Dv50 particle size of the second amorphous carbon is smaller than the Dv50 particle size of the first amorphous carbon, and the sphericity of the second amorphous carbon B is 0.7-1.0.

[0063] It should be noted that the massive structure of the first amorphous carbon refers to a non-spherical hard carbon structure, which can be a regular or irregular massive structure such as rod-shaped, plate-shaped or angular-shaped.

[0064] Since the carbonaceous particles contain first amorphous carbon particles and second amorphous carbon particles, the structure of the second amorphous carbon particles is spherical, and the Dv50 particle size of the second amorphous carbon particles is smaller than that of the first amorphous carbon particles. Therefore, the second amorphous carbon particles can fill the voids between multiple first amorphous carbon particles, thereby improving the compaction density. And since amorphous carbon particles are used, the present application can achieve an improvement in compaction density on the basis of ensuring a high sodium storage capacity.

[0065] In one embodiment, the ratio of the Dv50 particle size of the first amorphous carbon particles to that of the second amorphous carbon particles is 1:(0.1 - 0.6).

[0066] In one embodiment, the mass mixing ratio of the first amorphous carbon particles to the second amorphous carbon particles is 10:(0.5 - 7).

[0067] In one embodiment, the Dv50 of the first amorphous carbon particles is 4.0 μm - 10.0 μm, and the particle size distribution value S1 of the first amorphous carbon particles is 1.0 - 1.8, where the particle size distribution value S1 = (Dv90 - Dv10) / Dv50.

[0068] In one embodiment, the Dv50 of the second amorphous carbon particles is 1.0 μm - 4.0 μm, and the particle size distribution value S2 of the second amorphous carbon particles is 0.5 - 1.6, where the particle size distribution value S2 = (Dv90 - Dv10) / Dv50.

[0069] In one embodiment, the particle size distribution detection PSD (particle size distribution) detection result of the negative electrode material has a bimodal characteristic.

[0070] The embodiment of the present application also proposes a preparation method for the negative electrode material. Figure 3 The following is the preparation flow chart of the negative electrode material provided by the embodiment of the present application, which mainly includes three steps: S01, S02, and S03:

[0071] S01: Preparation of the material of the first amorphous carbon particles

[0072] The hard carbon precursor is subjected to raw material pretreatment, pre-carbonization, pulverization, first high-temperature carbonization, and first screening and demagnetization to obtain the first amorphous carbon particles.

[0073] In one embodiment, the temperature of the pre-carbonization is 300°C - 600°C, and the temperature of the first high-temperature carbonization is 1200°C - 1500°C.

[0074] S02: Preparation of the material of the second amorphous carbon particles

[0075] First, a spherical amorphous carbon precursor is prepared by hydrothermal treatment of polysaccharide and in-situ polymerization of polymer resin, and then the second amorphous carbon particles are obtained through processes such as the second high-temperature carbonization, pulverization, and the second sieving and demagnetization. It should be noted that other preparation methods of spherical carbon materials that can obtain the same powder parameters can also be used in this application.

[0076] In one embodiment, the temperature of the second high-temperature carbonization is 1200°C - 1500°C.

[0077] S03: Mixing the first amorphous carbon particles and the second amorphous carbon particles

[0078] The first amorphous carbon particles and the second amorphous carbon particles are mixed in a certain proportion to obtain the high-compaction composite amorphous carbon negative electrode material provided in the embodiment of this application. The mixing method can be mechanical mixing or direct mixing during the homogenization process of the electrode sheet. The embodiment of this application does not limit the mixing method.

[0079] It should be understood that the order of S01 and S02 is not fixed. In one embodiment, the first amorphous carbon particles can be prepared first, then the second amorphous carbon particles are prepared, and finally the first amorphous carbon particles and the second amorphous carbon particles are mixed in a certain proportion. In another embodiment, the second amorphous carbon particles can be prepared first, then the first amorphous carbon particles are prepared, and finally the first amorphous carbon particles and the second amorphous carbon particles are mixed in a certain proportion.

[0080] Among them, the first amorphous carbon particles are the amorphous carbon material component, and the second amorphous carbon particles are the amorphous carbon material component. More specifically, the first amorphous carbon particles are irregular block materials obtained by pretreatment, high-temperature carbonization, and crushing of the hard carbon precursor. The second amorphous carbon particles are spherical hard carbon materials prepared by hydrothermal treatment of polysaccharide and in-situ polymerization of polymer resin.

[0081] Optionally, the hard carbon precursor can be a biomass precursor (such as straw, rice husk), a synthetic resin precursor (such as phenolic resin), or an asphalt precursor and a sugar precursor. The embodiment of this application does not limit this.

[0082] The high-compaction hard carbon negative electrode material with composite components obtained by the above preparation method can significantly improve the tap density and the bulk density, thereby effectively improving the processing performance of the material, and can also improve the volume specific capacity while ensuring the mass specific capacity.

[0083] Furthermore, the negative electrode sheet made of this negative electrode material has excellent performance, the peel force will be effectively improved, and the sheet resistance will also be effectively reduced.

[0084] The following will elaborate on the anode material and preparation method provided by this application through specific embodiments.

[0085] Example 1

[0086] S01: Preparation of the material for the first amorphous carbon particles

[0087] Coconut shells are subjected to raw material pretreatment, pre-carbonization, crushing, high-temperature carbonization, screening, and demagnetization to obtain the first amorphous carbon particles. The obtained first amorphous carbon particles are in a block structure, specifically satisfying: Dv50 is 5.0 microns, and the particle size distribution value S1 ((Dv90 - Dv10) / Dv50) = 1.35.

[0088] S02: Preparation of the material for the second amorphous carbon particles

[0089] Spherical amorphous carbon precursors are prepared by in-situ polymerization of phenol and formaldehyde, and then the second amorphous carbon particles are obtained through processes such as high-temperature carbonization, crushing, screening, and demagnetization. The obtained spherical-structured second amorphous carbon particles are in a spherical hard carbon structure, specifically satisfying: Dv50 is 2.0 microns, the particle size distribution value S ((Dv90 - Dv10) / Dv50) = 1.55, and the sphericity is 0.98.

[0090] S03: Mixing the first amorphous carbon particles and the second amorphous carbon particles in a certain proportion

[0091] The first amorphous carbon particles and the second amorphous carbon particles are mixed in a mass ratio of 10:2 to obtain a high-compact sodium-ion battery amorphous carbon anode material with composite components.

[0092] Example 2

[0093] Adjust the mass mixing ratio of the first amorphous carbon particles and the second amorphous carbon particles. That is, the first amorphous carbon particles and the second amorphous carbon particles are mixed in a mass ratio of 10:3 to obtain a high-compact composite amorphous carbon anode material, and the other parameters are the same as those in Example 1.

[0094] Example 3

[0095] Adjust the mass mixing ratio of the first amorphous carbon particles and the second amorphous carbon particles. That is, the first amorphous carbon particles and the second amorphous carbon particles are mixed in a mass ratio of 10:5 to obtain a high-compact composite amorphous carbon anode material, and the other parameters are the same as those in Example 1.

[0096] Example 4

[0097] Change the Dv50 value of the first amorphous carbon particles, and adjust the Dv50 of the first amorphous carbon particles to 8.0 microns, and the other parameters are the same as those in Example 1.

[0098] Example 5

[0099] Change the Dv50 value of the second amorphous carbon particles, adjust the Dv50 of the second amorphous carbon particles to 4.0 μm, and the remaining parameters are the same as those in Example 1.

[0100] Example 6

[0101] Adjust the Dv50 values of the first amorphous carbon particles and the second amorphous carbon particles and adjust the mass mixing ratio of the first amorphous carbon particles and the second amorphous carbon particles to obtain composite amorphous carbon anode materials with different performances. The specific preparation process and requirements are as follows:

[0102] S01: Preparation of materials for the first amorphous carbon particles

[0103] The thermosetting resin is subjected to raw material pretreatment, pre-carbonization, pulverization, high-temperature carbonization, screening and demagnetization to obtain the first amorphous carbon particles. The obtained first amorphous carbon particles satisfy: Dv50 is 6.0 μm, and the particle size distribution value S1 ((Dv90 - Dv10) / Dv50) = 1.28.

[0104] S02: Preparation of materials for the second amorphous carbon particles

[0105] The spherical amorphous carbon precursor is prepared by the glucose hydrothermal method, and then the second amorphous carbon particles are obtained through processes such as high-temperature carbonization, pulverization, screening and demagnetization. The obtained spherical structure carbon second amorphous carbon particles satisfy that Dv50 is 2.5 μm, the particle size distribution value S ((Dv90 - Dv10) / Dv50) = 1.49, and the sphericity is 0.85.

[0106] S03: Proportion mixing of the first amorphous carbon particles and the second amorphous carbon particles

[0107] Mix the first amorphous carbon particles and the second amorphous carbon particles in a mass ratio of 10:4 to obtain a high-compact composite amorphous carbon anode material.

[0108] In order to more intuitively illustrate the influence of each specific parameter on the overall powder structure performance of the anode material, four comparative examples will also be exemplarily given in the embodiments of this application.

[0109] Comparative Example 1

[0110] The sample provided in this comparative example is a single first amorphous carbon particle, and the parameters of the first amorphous carbon particle are the same as those of the first amorphous carbon particle in Example 1.

[0111] Comparative Example 2

[0112] The sample provided in this comparative example is a single second amorphous carbon particle, and the parameters of the second amorphous carbon particle are the same as those of the second amorphous carbon particle in Example 1.

[0113] Comparative Example 3

[0114] In the sample provided in this comparative example, the particle size Dv50 of the second amorphous carbon particle is adjusted to 5.0 μm, and other parameters of the second amorphous carbon particle remain unchanged. The parameters of the first amorphous carbon particle are the same as those in Example 1.

[0115] Comparative Example 4

[0116] In the sample provided in this comparative example, the sphericity of the second amorphous carbon particle is adjusted to 0.2, that is, the morphology of the second amorphous carbon particle is adjusted, and other parameters remain unchanged. The parameters of the first amorphous carbon particle are the same as those in Example 1.

[0117] The performance tests were respectively carried out on the anode materials prepared in the above Examples 1-6, the anode materials prepared in Comparative Examples 1-4, and the corresponding sodium ion batteries. The test results are shown below:

[0118] In some embodiments of the present application, the morphology and structure of the anode material provided in the embodiments of the present application are scanned by an electron microscope, as the basis for further analysis, see Figure 4 and Figure 5 . Among them, Figure 4 is the microstructural diagram of the high-compaction sodium-ion amorphous carbon anode material provided in the embodiments of the present application, Figure 5 is the microstructural section diagram of the high-compaction sodium-ion amorphous carbon anode material provided in the embodiments of the present application. As shown in Figure 4 and Figure 5 , the first amorphous carbon particle is a block structure, the second amorphous carbon particle is a spherical hard carbon structure, and the uniform mixing and distribution of the first amorphous carbon particle and the second amorphous carbon particle effectively ensure the effective electrical contact between the particles. At the same time, it also ensures the effective and rapid transmission of electrons and ions during the charge and discharge process of the battery.

[0119] In other embodiments of the present application, other microscopic techniques can also be used for material characterization, such as optical microscopes, atomic force microscopes, etc. The embodiments of the present application do not limit this.

[0120] In some embodiments of the present application, in order to systematically characterize the influence of each parameter on the overall powder structure performance of the anode material, the above samples (including examples and comparative examples) were subjected to technical characterization of the tapped density and the compacted density, as shown in Table 1 below.

[0121]

[0122] Table 1.

[0123] As described above, Comparative Example 1 is a single first amorphous carbon particle, and Comparative Example 2 is a single second amorphous carbon particle. Examples 1 to 6 are all composite components, that is, a mixture of the first amorphous carbon particle and the second amorphous carbon particle. As shown in Table 1, compared with Comparative Example 1 and Comparative Example 2, the tapped density and the compaction density of Examples 1 to 6 have been significantly improved. Thus, it can be seen that the composite strategy of the first amorphous carbon particle and the second amorphous carbon particle can improve the performance of the corresponding samples. Compared with Example 1, Comparative Example 3 increased the particle size of the second amorphous carbon particle. As shown in Table 1, when the particle size of the second amorphous carbon particle becomes larger compared with Example 1, the compaction density of the sample will become correspondingly lower. Compared with Example 1, Comparative Example 4 decreased the sphericity of the second amorphous carbon particle and adjusted the morphology of the second amorphous carbon particle. As shown in Table 1, when the sphericity becomes smaller compared with Example 1, the tapped density and the compaction density of the sample will be correspondingly reduced.

[0124] Furthermore, in order to characterize the role of the material in improving the sodium battery electrochemical performance, we characterized the coin cell test capacity, Coulomb efficiency, electrode compaction, membrane resistance, etc. of the material.

[0125] As shown in Table 2, compared with Comparative Example 1 and Comparative Example 2, the compaction density of the sample materials provided by Examples 1 to 6 with composite components has been greatly improved. Correspondingly, the energy density of the battery can be synchronously improved. Compared with Comparative Example 1 and Comparative Example 2, the membrane resistance of the sample materials provided by Examples 1 to 6 with composite components is greatly reduced, so that the battery polarization can be effectively improved, and then the electrochemical performance of the battery can be improved. Compared with Comparative Example 1 and Comparative Example 2, the volume specific capacity of the sample materials provided by Examples 1 to 6 with composite components has been effectively improved. Among them, the volume specific capacity = the mass specific capacity * the compaction density.

[0126] In addition, through the performance characterization comparison between Example 1 and Comparative Example 3, it can be seen that the particle size of the second amorphous carbon particle will have a great influence on the electrochemical performance of the composite anode material. Specifically, the larger the particle size of the second amorphous carbon particle, the greater the membrane resistance, the smaller the volume specific capacity, and the smaller the mass specific capacity of the composite anode material.

[0127] Through the performance characterization comparison between Example 1 and Comparative Example 4, it can be seen that the morphological characteristics of the second amorphous carbon particle will have a relatively large influence on the electrochemical performance of the composite anode material. Specifically, the smaller the sphericity of the second amorphous carbon particle, the greater the membrane resistance, the smaller the volume specific capacity, the smaller the mass specific capacity, and the smaller the compaction density of the composite anode material.

[0128]

[0129] Table 2

[0130] In summary, on the one hand, the technical characterization of the negative electrode material with a composite component is significantly better than that of the negative electrode material with a single component; on the other hand, the Dv50 value of the second amorphous carbon particles needs to be less than the Dv50 value of the first amorphous carbon particles, and the sphericity of the second amorphous carbon particles also needs to be controlled within a certain value.

[0131] The embodiment of the present application also provides a negative electrode sheet, which includes a negative electrode current collector and a negative electrode material layer provided on at least one side of the negative electrode current collector. The negative electrode material layer includes the above-mentioned negative electrode material or the negative electrode material prepared by the above-mentioned preparation method.

[0132] The embodiment of the present application also provides a sodium ion battery, which includes a positive electrode sheet, a negative electrode sheet, a separator located between the positive electrode sheet and the negative electrode sheet, and an electrolyte. The electrolyte is filled between the positive electrode sheet and the negative electrode sheet. The negative electrode sheet includes a negative electrode material or a negative electrode material prepared by a related preparation method.

[0133] The embodiment of the present application also provides an electronic device, which includes a housing, electronic components and a battery accommodated in the housing. The battery powers the electronic components, and the battery includes the above-mentioned sodium ion battery.

[0134] The electronic device can be, for example, a mobile phone, a smart screen, a tablet computer, a personal computer (PC), a personal digital assistant (PDA), a smart watch, a mobile power supply, a netbook, a wearable device, an augmented reality (AR) device, a virtual reality (VR) device, a vehicle-mounted device, an energy storage device, a base station, and an automobile, etc. The embodiment of the present application does not impose any special restrictions on the specific form of the electronic device.

[0135] In some solutions, multiple embodiments of the present application can be combined and the combined solution can be implemented. Optionally, some operations in the processes of the method embodiments are optionally combined, and / or the order of some operations is optionally changed. Moreover, the execution order between the steps of each process is only exemplary and does not constitute a limitation on the execution order between the steps. The steps can also be in other execution orders. It is not intended to indicate that the execution order is the only order in which these operations can be performed.

[0136] Those of ordinary skill in the art will think of various ways to reorder the operations described in the embodiments of the present application. In addition, it should be noted that the process details involved in a certain embodiment of the present application are equally applicable to other embodiments in a similar manner, or different embodiments can be combined and used.

[0137] In addition, some steps in the method embodiments can be equivalently replaced by other possible steps. Or, some steps in the method embodiments can be optional and can be deleted in certain usage scenarios. Or, other possible steps can be added to the method embodiments. Moreover, the method embodiments can be implemented independently or in combination. The above content is only the specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions within the technical scope disclosed in the present application should be covered by the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

[0138] In addition, the present application mainly describes in detail the sodium battery anode material. It should be emphasized that the design concept of this composite material also has the same guiding significance for the material design in other fields. Therefore, patents arranged in other fields with similar ideas are also within the protection scope of the present application.

Claims

1. A negative electrode material, characterized in that, The negative electrode material includes carbonaceous particles, and the carbonaceous particles include first amorphous carbon particles and second amorphous carbon particles. The first amorphous carbon particles have a block structure, and the second amorphous carbon particles have a spherical hard carbon structure. The Dv50 particle size of the second amorphous carbon particles is smaller than that of the first amorphous carbon particles, and the sphericity of the second amorphous carbon particles B is 0.7 - 1.

0.

2. The negative electrode material according to claim 1, characterized in that The ratio of the Dv50 particle size of the first amorphous carbon particles to that of the second amorphous carbon particles is 1:(0.1 - 0.6).

3. The negative electrode material according to claim 1 or 2, characterized in that, The mass ratio of the first amorphous carbon particles to the second amorphous carbon particles is 10:(0.5 - 7).

4. The negative electrode material according to any one of claims 1 to 3, characterized in that, The Dv50 of the first amorphous carbon particles is 4.0 microns - 10.0 microns, and the particle size distribution value S1 of the first amorphous carbon particles is 1.0 - 1.

8. The particle size distribution value S1 = (Dv90 - Dv10) / Dv50.

5. The negative electrode material according to any one of claims 1-4, characterized in that, The Dv50 of the second amorphous carbon particles is 1.0 microns - 4.0 microns, and the particle size distribution value S2 of the second amorphous carbon particles is 0.5 - 1.

6. The particle size distribution value S2 = (Dv90 - Dv10) / Dv50.

6. The negative electrode material according to any one of claims 1-5, characterized in that, The PSD test result of the particle size distribution of the negative electrode material has a bimodal characteristic.

7. A method for preparing a negative electrode material, characterized in that, The method includes: Subjecting the hard carbon precursor to pretreatment, pre-carbonization, pulverization, first high-temperature carbonization, and first sieving and demagnetization to obtain first amorphous carbon particles with a block structure; Using the polysaccharide hydrothermal method and in-situ polymerization of polymer resin to prepare a spherical amorphous carbon precursor, and subjecting the spherical amorphous carbon precursor to second high-temperature carbonization, pulverization, and second sieving and demagnetization to obtain second amorphous carbon particles with a spherical hard carbon structure; Mixing the first amorphous carbon particles and the second amorphous carbon particles to obtain the negative electrode material.

8. The preparation method according to claim 7, characterized in that, Mixing the first amorphous carbon particles and the second amorphous carbon particles to obtain the negative electrode material includes: Mixing the first amorphous carbon particles and the second amorphous carbon particles according to a mass ratio of 10:(0.5 - 7) to obtain the negative electrode material.

9. The preparation method according to claim 7 or 8, characterized in that, The Dv50 particle size of the second amorphous carbon particles is smaller than that of the first amorphous carbon particles.

10. The preparation method according to any one of claims 7-9, characterized in that, The sphericity of the second amorphous carbon particles is 0.7 - 1.

0.

11. A negative electrode plate, characterized in that, The negative electrode sheet includes a negative electrode current collector and a negative electrode material layer provided on at least one side of the negative electrode current collector. The negative electrode material layer includes the negative electrode material according to any one of claims 1 - 6 or the negative electrode material prepared by the preparation method according to any one of claims 7 - 10.

12. A sodium-ion battery, characterized in that, The sodium ion battery includes a positive electrode sheet, a negative electrode sheet, a separator located between the positive electrode sheet and the negative electrode sheet, and an electrolyte. The electrolyte is filled between the positive electrode sheet and the negative electrode sheet. The negative electrode sheet includes the negative electrode material according to any one of claims 1 - 6 or the negative electrode material prepared by the preparation method according to any one of claims 7 - 10.

13. An electronic device, characterized in that, The electronic device includes a housing, and electronic components and a battery accommodated in the housing. The battery supplies power to the electronic components, and the battery includes the sodium-ion battery described in claim 12.

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